it's possible to save materials in cycles node editor to reuse them in other project?
You can create a .blend file that is a master collection of your finished materials, and then Link (not Append) this to your various other .blends. 



Be cautious with this kind of workflow though, because if you change anything in this master file it means your materials in all other .blends may render differently - so for example, re-rendered frames of animation may look different.

It's generally best to work with Linked files on a project basis, not a global basis.